Plasma Spectroscopy

Takashi Fujimoto

Abstract

This book presents a theoretical framework of plasma spectroscopy, in which the observed spectral line intensities or the populations of excited levels of atoms or ions immersed in plasma are interpreted in terms of the characteristics of the plasma. Following a review of important atomic processes in plasma, the rate equation governing the populations in excited levels and the ground state is solved in the collisional-radiative model. In this model, plasmas are classified into the ionizing plasma and the recombining plasma. Various features of these plasmas are examined. Ionization and recomb ... More

This book presents a theoretical framework of plasma spectroscopy, in which the observed spectral line intensities or the populations of excited levels of atoms or ions immersed in plasma are interpreted in terms of the characteristics of the plasma. Following a review of important atomic processes in plasma, the rate equation governing the populations in excited levels and the ground state is solved in the collisional-radiative model. In this model, plasmas are classified into the ionizing plasma and the recombining plasma. Various features of these plasmas are examined. Ionization and recombination of atoms and ions are also treated in the model. An emission-line intensity is proportional to the ionization flux or to the recombination flux, and thus the ionization-balance plasma produces less intense emission lines. The recombination continuum intensity continues smoothly to the series lines, originating from levels in local thermodynamic equilibrium, so that the Boltzmann plot of the population of these levels is extended to the continuum-state electrons. Line broadening mechanisms are discussed, including the Stark broadening. Radiation transport gives rise to a modification to the emission line profile and to an effective decrease in the transition probability; the latter problem is treated in two alternative approaches. Phenomena characteristic of dense plasma are discussed, including the excitation and deexcitation processes of ions involving doubly excited levels and a modification to the Saha relationship.

End Matter

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